It has been known since Vernon K. Krieble's patent, U.S. Pat. No. 3,046,262, to use saccharin (benzoic sulfimide) as an accelerator of anaerobically curing acrylic compositions. The same reference, and many since, teach that sulfimides generally are useful as accelerators. Sulfimides are compounds having a divalent group of the structure: ##STR1## where both the sulfonyl and the carbonyl groups are linked to hydrocarbon groups.
In U.S. Pat. No. 4,447,588 there are described anaerobically curing compositions free of peroxides which include sulfimide accelerator compounds. Saccharin and C.sub.6 H.sub.5 --SO.sub.2 NH--CO--C.sub.6 H.sub.5 are described as suitable sulfimide accelerators in these systems.
Sulfimides, such as saccharin, have certain limitations in anaerobic systems which it is desirable to overcome. Sulfimides typically have only limited solubility in organic resin systems and this solubility problem is worse for silicones. Saccharin is virtually insoluble in polyorganosiloxane resins. This solubility problem has severely limited extension of anaerobic curing technology, for instance in the area of anaerobically curing silicone formulations. Saccharin has also been identified as a weak carcinogen in laboratory animals, a fact which has led to a recent proposal to require cancer warning labels on all products containing saccharin. Further, the environmental mobility of small molecules generally makes it desirable that all components in curable systems be chemically bound to polymer backbones, at least in the fully cured resin. Because of these factors there is a need for new types of anaerobic accelerators which can be designed according to the solubility, acceleration efficiency, environmental mobility and other requirements of a particular formulation.
In U.S. Pat. No. 4,443,587 there are described malonylsulfamide compounds having the structure: ##STR2## These compounds are reported to be useful as accelerators of peroxide initiated polymerizations of ethylenically unsaturated compounds such as (meth)-acrylic ethers.
In U.S. Pat. No. 4,429,063, there are described anaerobically curing acrylic monomer compositions containing open chain symmetric sulfamides containing the central group: ##STR3## These compounds are prepared by reaction of sulfonyl diisocyanate with an alcohol or a carboxylic acid. They are reported to be useful as stabilizers of anaerobic polymerizations.
In the copending application of A. Jacobine, Ser. No. 650,750, filed Sept. 13, 1984, now U.S. Pat. No. 4,513,127, there are described anaerobic compositions which include as accelerators derivatives of aromatic sulfonyl isocyanates and compounds containing reactive hydrogen groups. The reactive hydrogen containing compound may, for instance, be a hydroperoxide, an acrylic functional compound such as hydroxyethylmethacrylate, a silicone bindable compound such as propargyl alcohol or other aliphatically unsaturated alcohols or 3-mercaptopropyltrimethoxysilane, etc.